viewer: fixed reappearing swiped snack bar

lib/widgets/common/action_mixins/feedback.dart

@@ -7,6 +7,7 @@ import 'package:aves/model/settings/settings.dart';
 import 'package:aves/services/accessibility_service.dart';
 import 'package:aves/theme/durations.dart';
 import 'package:aves/theme/icons.dart';
+import 'package:aves/widgets/common/action_mixins/overlay_snack_bar.dart';
 import 'package:aves/widgets/common/basic/circle.dart';
 import 'package:aves/widgets/common/extensions/build_context.dart';
 import 'package:aves/widgets/viewer/entry_viewer_page.dart';
@@ -58,24 +59,22 @@ mixin FeedbackMixin {
           (context) => SafeArea(
             child: Padding(
               padding: margin,
-              child: SnackBar(
+              child: OverlaySnackBar(
                 content: snackBarContent,
-                animation: const AlwaysStoppedAnimation<double>(1),
                 action: action != null
-                    ? SnackBarAction(
+                    ? TextButton(
-                        label: action.label,
+                        style: ButtonStyle(
+                          foregroundColor: MaterialStateProperty.all(Theme.of(context).snackBarTheme.actionTextColor),
+                        ),
                         onPressed: () {
-                          // the regular snack bar dismiss behavior is confused
-                          // because it expects a `Scaffold` in context,
-                          // so we manually dimiss the overlay entry
-                          // TODO TLAD [bug] after dismissing the overlay, tapping on the snack bar area makes the overlay visible again
                           notificationOverlayEntry?.dismiss();
                           action.onPressed();
                         },
+                        child: Text(action.label),
                       )
                     : null,
-                duration: duration,
                 dismissDirection: DismissDirection.horizontal,
+                onDismiss: () => notificationOverlayEntry?.dismiss(),
               ),
             ),
           ),

lib/widgets/common/action_mixins/overlay_snack_bar.dart

@@ -0,0 +1,135 @@
+import 'package:flutter/material.dart';
+
+// adapted from Flutter `SnackBar` in `/material/snack_bar.dart`
+
+// As of Flutter v3.0.1, `SnackBar` is not customizable enough to add margin
+// and ignore pointers in that area, so we use an overlay entry instead.
+// This overlay entry is not below a `Scaffold` (which is expected by `SnackBar`
+// and `SnackBarAction`), and is not dismissed the same way.
+// This adaptation assumes the `SnackBarBehavior.floating` behavior and no animation.
+class OverlaySnackBar extends StatelessWidget {
+  final Widget content;
+  final Widget? action;
+  final DismissDirection dismissDirection;
+  final VoidCallback onDismiss;
+
+  const OverlaySnackBar({
+    super.key,
+    required this.content,
+    required this.action,
+    required this.dismissDirection,
+    required this.onDismiss,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final colorScheme = theme.colorScheme;
+    final snackBarTheme = theme.snackBarTheme;
+    final isThemeDark = theme.brightness == Brightness.dark;
+    final buttonColor = isThemeDark ? colorScheme.primary : colorScheme.secondary;
+
+    final brightness = isThemeDark ? Brightness.light : Brightness.dark;
+    final themeBackgroundColor = isThemeDark ? colorScheme.onSurface : Color.alphaBlend(colorScheme.onSurface.withOpacity(0.80), colorScheme.surface);
+    final inverseTheme = theme.copyWith(
+      colorScheme: ColorScheme(
+        primary: colorScheme.onPrimary,
+        secondary: buttonColor,
+        surface: colorScheme.onSurface,
+        background: themeBackgroundColor,
+        error: colorScheme.onError,
+        onPrimary: colorScheme.primary,
+        onSecondary: colorScheme.secondary,
+        onSurface: colorScheme.surface,
+        onBackground: colorScheme.background,
+        onError: colorScheme.error,
+        brightness: brightness,
+      ),
+    );
+
+    final contentTextStyle = snackBarTheme.contentTextStyle ?? ThemeData(brightness: brightness).textTheme.subtitle1;
+
+    const horizontalPadding = 16.0;
+    final padding = EdgeInsetsDirectional.only(start: horizontalPadding, end: action != null ? 0 : horizontalPadding);
+    const actionHorizontalMargin = horizontalPadding / 2;
+    const singleLineVerticalPadding = 14.0;
+
+    Widget snackBar = Padding(
+      padding: padding,
+      child: Row(
+        children: <Widget>[
+          Expanded(
+            child: Container(
+              padding: const EdgeInsets.symmetric(vertical: singleLineVerticalPadding),
+              child: DefaultTextStyle(
+                style: contentTextStyle!,
+                child: content,
+              ),
+            ),
+          ),
+          if (action != null)
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: actionHorizontalMargin),
+              child: TextButtonTheme(
+                data: TextButtonThemeData(
+                  style: TextButton.styleFrom(
+                    primary: buttonColor,
+                    padding: const EdgeInsets.symmetric(horizontal: horizontalPadding),
+                  ),
+                ),
+                child: action!,
+              ),
+            ),
+        ],
+      ),
+    );
+
+    final elevation = snackBarTheme.elevation ?? 6.0;
+    final backgroundColor = snackBarTheme.backgroundColor ?? inverseTheme.colorScheme.background;
+    final shape = snackBarTheme.shape ?? const RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(4.0)));
+
+    snackBar = Material(
+      shape: shape,
+      elevation: elevation,
+      color: backgroundColor,
+      child: Theme(
+        data: inverseTheme,
+        child: snackBar,
+      ),
+    );
+
+    const topMargin = 5.0;
+    const bottomMargin = 10.0;
+    const horizontalMargin = 15.0;
+    snackBar = Padding(
+      padding: const EdgeInsets.fromLTRB(
+        horizontalMargin,
+        topMargin,
+        horizontalMargin,
+        bottomMargin,
+      ),
+      child: snackBar,
+    );
+
+    snackBar = SafeArea(
+      top: false,
+      bottom: false,
+      child: snackBar,
+    );
+
+    snackBar = Semantics(
+      container: true,
+      liveRegion: true,
+      onDismiss: onDismiss,
+      child: Dismissible(
+        key: const Key('dismissible'),
+        direction: dismissDirection,
+        resizeDuration: null,
+        onDismissed: (direction) => onDismiss(),
+        child: snackBar,
+      ),
+    );
+
+    return snackBar;
+  }
+}

pubspec.yaml

@@ -146,6 +146,9 @@ flutter:
 #  `OutputBuffer` in `/services/common/output_buffer.dart`
 #  adapts from Flutter `_OutputBuffer` in `/foundation/consolidate_response.dart`
 #
+#  `OverlaySnackBar` in `/widgets/common/action_mixins/overlay_snack_bar.dart`
+#  adapts from Flutter `SnackBar` in `/material/snack_bar.dart`
+#
 #  `EagerScaleGestureRecognizer` in `/widgets/common/behaviour/eager_scale_gesture_recognizer.dart`
 #  adapts from Flutter `ScaleGestureRecognizer` in `/gestures/scale.dart`
 #